Hint Based Media Content Streaming

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for media content streaming can include communicating with a remote device to stream media content to the remote device, accessing hint information associated with the media content, and transmitting a data stream to the remote device based on the hint information. The hint information can include message headers arranged in a transmission order sequence that correspond to respective media data samples. Accessing hint information can include accessing a hint segment that includes the message headers interleaved with the media data samples.

PRIORITY CLAIM

This patent document is a continuation, and claims the benefits ofpriority under 35 USC 120, of U.S. application Ser. No. 12/542,582,entitled “HINT BASED MEDIA CONTENT STREAMING,” filed Aug. 17, 2009 (nowU.S. Pat. No. 8,166,191), which is incorporated herein by reference inits entirety.

BACKGROUND

This specification relates to streaming media content.

A networked server can stream media content to one or more computersconnected to a communication network. Various examples of media contentinclude video, audio, text, and combinations thereof. A computer canrequest and receive media content. A computer can render media contentto an output device such as a video display, speaker, or a printer.

Some servers can use one or more protocols such as the Real-TimeMessaging Protocol (RTMP) of Adobe Systems Incorporated of San Jose,Calif. to send media content over a network such as one based on anInternet Protocol (IP). RTMP can provide multiplexing and packetizingservices for a higher-level multimedia stream protocol. RTMP messagescan include a timestamp and payload type identification information.Protocols such as RTMP can use a reliable transport protocol such asTransmission Control Protocol (TCP) to provide guaranteedtimestamp-ordered end-to-end delivery of messages, across one or morestreams.

SUMMARY

This specification describes technologies relating to media contentstreaming based on hint information.

In one aspect, methods for media content streaming can includecommunicating with a remote device to stream media content to the remotedevice. The methods can include accessing hint information associatedwith the media content. The hint information can include message headersarranged in a transmission order sequence that can correspond torespective media data samples. A message header can include a messagestream identifier, a message type identifier, a timestamp, and a messagelength value. The methods can include transmitting a data stream to theremote device. A data stream can include messages that are based on themessage headers. A data stream can include messages arranged in atransmission order sequence. A message can include a message header anda media data sample. Other implementations can include correspondingsystems, apparatus, and computer programs, configured to perform theactions of the methods, encoded on computer storage devices.

These and other implementations can include one or more of the followingfeatures. Separate ones of the transmitted messages can be based on adifferent one of the message headers and a corresponding different oneof the media data samples. Accessing hint information can includeaccessing a hint segment that includes the message headers interleavedwith the media data samples. Separate ones of the media data samples canbe arranged as message payload data for corresponding ones of themessage headers. A hint segment can include a media data sampleassociated with audio data interleaved with a media data sampleassociated with video data. Transmitting the data stream to the remotedevice can include multiplexing first messages that include audio datawith second messages that include video data on the data stream.Accessing hint information can include accessing a hint segment thatincludes the message headers interleaved with pointers to correspondingmedia data samples. Transmitting the data stream to the remote devicecan include transmitting the data stream in accordance with a Real-TimeMessaging Protocol (RTMP). Each message header can be arranged accordingto a RTMP message header format. These and other implementations caninclude operating a server to deliver multiple streams to remote devicesbased on information including the hint information

These and other implementations can include accessing a document thatincludes a hint segment, a media metadata track associated with at leasta portion of the media data samples, and a hint metadata track. The hintsegment can include the message headers interleaved with the media datasamples. The hint metadata track can include pointers to respective onesof the message headers. The media metadata track can include pointers torespective associated ones of the media data samples within the hintsegment.

In another aspect, methods for media content streaming can includecausing a processor to use hint information associated with mediacontent to transmit a data stream and receiving the data stream. Thehint information can include message headers, arranged in a transmissionorder sequence, that correspond to respective media data samples, whereseparate ones of the message headers include a message streamidentifier, a message type identifier, a timestamp, and a message lengthvalue. A data stream can include messages arranged in the transmissionorder sequence, where separate ones of the messages are based on adifferent one of the message headers and a corresponding different oneof the media data samples. Other implementations can includecorresponding systems, apparatus, and computer programs, configured toperform the actions of the methods, encoded on computer storage devices.

These and other implementations can include one or more of the followingfeatures. Receiving the data stream comprises can include multiplexedfirst messages that include audio data with second messages that includevideo data on the data stream. Receiving the data stream can includereceiving the data stream in accordance with a RTMP. Each message headercan be arranged according to a RTMP message header format.

In another aspect, media content streaming systems can include one ormore remote device configured to request and receive media content, andone or more endpoints, operable to interact with the remote device, thatare configured to perform one or more of the operations describedherein.

Particular embodiments of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. One or more of the described technologies canincrease media content streaming throughput. One or more of thedescribed technologies can decrease an amount of computer storage spacerequired to store a media document, and a smaller document size candecrease document access latency. One or more of the describedtechnologies can decrease media stream packet construction times and canmake these times more predictable. One or more of the describedtechnologies can increase the number of concurrent streams handled by aserver.

The details of one or more embodiments of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages of thesubject matter will become apparent from the description, the drawings,and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an example of a communication network connected withcomputing devices.

FIG. 2 shows an example of a RTMP header and corresponding payload.

FIG. 3 shows a media document example with hint samples including a RTMPheader and a sample pointer.

FIG. 4 shows a media document example with hint samples including a RTMPheader and a sample.

FIG. 5 shows a media document example in accordance with anon-duplication format.

FIG. 6 shows an example of pointer relationships in a media document.

FIG. 7 shows an examples of a server streaming data from a document.

FIG. 8 shows an example of a media content streaming technique.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 shows an example of a communication network connected withcomputing devices. Network endpoints 105, 110, 120, 125 can connect to acommunication network 115 such as the Internet or a Local Area Network(LAN). Examples of endpoints 105, 110, 120, 125 can include computingdevices such as a mobile phone, personal computer 105, 110 or a computersuch as a server 120, 125. An endpoint can include one or moreprocessors that can be programmed or configured to perform one or moreoperations mentioned in the present disclosure. In some implementations,a processor can include multiple processors or processor cores. Anetwork endpoint can be identified as a client, a server, or both, butin any case, a network endpoint necessarily includes some hardware sinceit includes a physical device.

Endpoints 105, 110, 120, 125 can access electronic documents such asmedia documents. An electronic document (which for brevity will simplybe referred to as a document) does not necessarily correspond to a file.A document may be stored in a portion of a file that holds otherdocuments, in a single file dedicated to the document in question, or inmultiple coordinated files. The document need not be a text file or adocument in the sense of a word processor. The document can includeaudio, video, images, and data content. In other examples, the documentcan be any audio, video, image, or data file. Also the document can bestreaming versions of the aforementioned document types.

Endpoints 105, 110, 120, 125 can establish connections with otherendpoints 105, 110, 120, 125. For example, servers 120, 125 canestablish connections with other servers 120, 125 or with computers 105,110. For example, computers 105, 110 can establish connections withother computers 105, 110 or with servers 120, 125. In someimplementations, TCP/IP can transport data between network endpoints105, 110, 120, 125. In some implementations, network endpoints 105, 110,120, 125 can communicate with each other using RTMP over TCP/IP. Forexample, a computer 105 can receive a media stream from a server 120using RTMP.

A network endpoint can run one or more applications that include supportfor RTMP such as ADOBE® FLASH® Player and/or ADOBE® AIR® software,available from Adobe Systems Incorporated, of San Jose, Calif. Forexample, some servers can use RTMP to stream ADOBE® FLASH® content. Insome implementations, a server such as an one configured as an ADOBE®FLASH® Media Interactive Server (FMS) can stream media content to anendpoint running ADOBE® FLASH® Player. A FMS can access mediainformation such as a FLASH® Video (e.g., F4V) document to obtain mediacontent. A F4V based document can include media content and can be inaccordance with an International Organization for Standardization (ISO)Base Media File Format.

A server can process a request from a client that requests mediacontent. In some implementations, a server cluster containing multipleservers can process requests from clients in a distributed fashion. Aserver can stream media content over a network such as the Internet to aclient. In some implementations, streaming media content can includesending RTMP messages that include one or more media data samples suchas audio samples and video samples. A server can access a document suchas one in accordance with a MPEG4 format to obtain media data samples.

Servers can use hint information to process media content. Some documentformats such as ones based on an ISO MPEG4 format can support aninclusion of hint information. Hint information can include a hint mediadata segment and can include a hint metadata track.

Hint media data can include one or more hint samples. A hint sample caninclude a network protocol header. In some implementations, a hintsample can include a network protocol header and one or more of an audiosample, video sample, or another type of sample such as text. In someimplementations, a hint sample can include a network protocol header anda pointer to a sample in a different media data segment in lieu ofcontaining the sample itself.

In some implementations, a server can use information in a hint mediadata segment to stream media content. A hint metadata track can containpointers to locations of hint samples in a hint media data segment of adocument. In some implementations, a server can use information in ahint metadata track and a corresponding hint media data segment tostream media content.

In some implementations, a hint sample can include a RTMP header. Acorresponding RTMP hint metadata track can include a pointer to a hintsample, containing a RTMP header, in a RTMP hint media data segment.Hint media data can include hint samples associated with different mediadata sample types. In some implementations, a document can include onesegment of multiplexed hint media data containing RTMP headers andcorresponding payload information. Payload information can include apayload prepared for transmission or a pointer to obtain data toconstruct a payload portion of a message. For example, one hint mediadata segment in a document can include multiplexed audio and videoinformation associated with a movie. The RTMP packet information in ahint media data segment can be arranged by timestamp.

FIG. 2 shows an example of a RTMP header and corresponding payload. ARTMP message 200 can include a RTMP header 201 and a correspondingpayload 202. A RTMP header 201 can include a message stream identifier205, a message type identifier 210, a timestamp 215, and a messagelength value 220. In some stream communications, a payload 202 includingdata can immediately follow a corresponding RTMP header 200.

FIG. 3 shows a media document example with hint samples including a RTMPheader and a sample pointer. A document 300 can include one or moresegments of media data such as audio media data 305, video media data310, and hint media data 315. In some implementations, a document 300can include media data such as text. Audio media data 305 can includeone or more audio samples 320, 323. Video media data 310 can include oneor more video samples 325, 327. Hint media data 315 can include one ormore hint samples 330, 332, 334, 336.

A hint sample 330, 332, 334, 336 can include a RTMP header and a samplepointer such as one pointing to a location of an audio sample 320, 323or a video sample 325, 327. In some implementations, hint samples 330,332, 334, 336 are arranged in a transmission order sequence. Forexample, an endpoint can access hint samples 330, 332, 334, 336 in hintmedia data 315 to construct messages to stream to a client. Constructinga stream message can include accessing a media sample 320, 325, 323, 327based on a sample pointer in a hint sample 330, 332, 334, 336.

The document 300 can include a movie box 340 to describe the contents ofthe media data 305, 310, 315. Movie box 340 is not limited to describingmovie data, but can describe other content. The movie box 340 caninclude metadata tracks such as an audio track 345, a video track 350,and a RTMP hint track 355 that respectively corresponds to audio mediadata 305, video media data 310, and hint media data 315. In someimplementations, various movie box tracks 345, 350, 355 can includepointers to locations of samples in respective media data 305, 310, 315.In some implementations, a movie box 340 can include information aboutrandom access samples in one or more media data segments, suchinformation can be used for seeking.

In some implementations, an endpoint can render a movie to a displaybased on the sequence of pointers contained in tracks such as an audiotrack 345 and a video track 350. In some implementations, an endpointcan render a movie to a display based on the sequence of pointerscontained in a RTMP hint track 355. In some implementations, an endpointcan stream a movie over a RTMP connection based on information such asan ordering of pointers in a RTMP hint track 355, an ordering of messagedata in a segment of hint media data 315, or a combination thereof.

FIG. 4 shows a media document example with hint samples including a RTMPheader and a sample. A document 400 can include one or more segments ofmedia data such as audio media data 405, video media data 410, and hintmedia data 415. In some implementations, a document 400 can includemedia data such as text. Audio media data 405 can include one or moreaudio samples 420, 423. Video media data 410 can include one or morevideo samples 425, 427. Hint media data 415 can include one or more hintsamples 430, 432, 434, 436.

A hint sample 430, 432, 434, 436 can include a RTMP header and a samplesuch as a duplicate one of a sample that is contained in a media datasegment such as an audio sample 420, 423 in an audio segment or a videosample 425, 427 in a video segment. In some implementations, hintsamples 430, 432, 434, 436 are arranged in a transmission ordersequence. For example, an endpoint can access hint samples 430, 432,434, 436 in hint media data 415 to stream messages to a client. In someimplementations, streaming messages can include directly sending a hintsample 430, 432, 434, 436, as is, in a data stream to a client. Forexample, a hint sample can be arranged as a properly formatted RTMPmessage that includes a media data sample such as audio, video, or textsituated as the message's payload. In some implementations, a server canmodify one or more portions of a RTMP message included in a hint samplebefore sending the RTMP message.

The document 400 can include a movie box 440 to describe the contents ofthe media data 405, 410, 415. Movie box 440 is not limited to describingmovie data, but can describe other content. The movie box 440 caninclude metadata tracks such as an audio track 445, a video track 450,and RTMP hint track 455 that respectively correspond to audio media data405, video media data 410, and hint media data 415. In someimplementations, various movie box tracks 445, 450, 455 can includepointers to locations of samples in respective media data 405, 410, 415.

In some implementations, an endpoint can render a movie to a displaybased on the sequence of pointers contained in tracks such as an audiotrack 445 and a video track 450. In some implementations, an endpointcan render a movie to a display based on the sequence of pointerscontained in a RTMP hint track 455. In some implementations, an endpointcan stream a movie over a RTMP connection based information such as anordering of pointers in a RTMP hint track 455, an ordering of messagedata in a segment of hint media data 415, or a combination thereof.

FIG. 5 shows a media document example in accordance with anon-duplication format. A server can generate a document in anon-duplication mode where media data samples are not duplicated betweendifferent media data segments such as video, audio, text and a hintmedia data segment. In some implementations, the media content stored ina hint media data segment of a document can suffice to generate amessages for a data stream. In some non-duplication formats, a mediadocument 500 can include a segment of hint media data 515 in lieu ofother segments of media data such as a video media data segment andaudio media data segment. In some implementations, a non-duplicationmode can reduce a size of a generated media document and can increase aserver's streaming throughput.

Hint media data 515 can include one or more hint samples 550, 552, 554,556. A hint sample 550, 552, 554, 556 can include a RTMP header and asample. In some hint samples, a hint sample 550, 554 can include a RTMPheader and an audio sample. In some other hint samples, a hint sample552, 556 can include a RTMP header and a video sample.

Hint media data 515 can include hint samples 550, 554 associated withaudio interleaved with hint samples 552, 556 associated with video. Insome implementations, hint samples 550, 552, 554, 556 are arranged in atransmission order sequence. For example, an endpoint can access hintsamples 550, 552, 554, 556 in hint media data 515 to stream messages toa client. In some implementations, streaming messages can includedirectly sending a hint sample 550, 552, 554, 556, as is, in a datastream to a client. For example, a hint sample can be arranged as aproperly formatted RTMP message with a sample contained in the hintsample situated as the message's payload.

In some implementations, a document 500 can include a movie box 540 todescribe the contents of hint media data 515. The movie box 540 caninclude metadata tracks such as an audio track 560, a video track 565,and RTMP hint track 570. The RTMP hint track 570 can include pointers toassociated hint samples 550, 552, 554, 556 in the hint media data 515.The audio track 560 can include pointers to locations of audio samplesin respective hint samples 550, 554 associated with audio. The videotrack 565 can include pointers to locations of video samples inrespective hint samples 552, 556 associated with video.

In some implementations, an endpoint can render a movie to a displaybased on the sequence of pointers contained in tracks such as an audiotrack 560 and a video track 565. In some implementations, an endpointcan render a movie to a display based on the sequence of pointerscontained in a RTMP hint track 570. In some implementations, an endpointcan stream a movie over a RTMP connection based on an ordering ofpointers in a RTMP hint track 570. In some implementations, an endpointcan stream a movie over a RTMP connection based on an ordering of hintmedia data 515.

FIG. 6 shows an example of pointer relationships in a media document. Adocument 600 can include hint media data 615. Hint media data 615 caninclude multiple hint samples 620, 625. A first hint sample 620 caninclude a header such as a RTMP header 630 and a corresponding payloadincluding a sample 632. A second hint sample 625 can include a headersuch as a RTMP header 635 and a corresponding payload including a sample637.

A document 600 can include multiple metadata tracks 645, 650, 655 thatcorrespond to one or more media types such as video, audio, text, orhint. The document 600 can include a first track 645 that includes apointer 647 to a location of a sample 632 of a first media type situatedin a hint sample 620. The document 600 can include a second track 650that includes a pointer 652 to a location of a sample 637 of a secondmedia type situated in a different hint sample 625.

A hint track 655 in the document 600 can include pointers 657, 659 tolocations of respective hint samples 620, 625. In some implementations,hint media data 600 can interleave hint samples 620, 625 associated withdifferent media types.

In some implementations, a document 600 can include pointerssynchronized for playback. In some implementations, pointers can besynchronized to an event or a specific time duration in media playbackor streaming. For example, pointers 647, 652 in the first and secondtracks 645, 650 can be synchronized to an event. Multiple hint pointers657, 659 in the hint track 655 can be synchronized to the same eventbased on their corresponding samples 632, 637 being related to theevent.

A server can convert a document without hint information to a documentthat includes hint information. A server can use a format such as oneindicated by the examples of FIGS. 3, 4, 5, and 6 to generate a documentwith hint information. In some implementations, a standalone softwareroutine can add hinting information to a document, which can be placedon a server for distribution. In some implementations, a server can usea non duplication mode to strip out media data segments and replace themwith one hint media data segment that contains their respective mediasample data; the server can modify one or more additional portions ofthe original document to reflect this change.

FIG. 7 shows an examples of a server streaming data from a document. Aserver 700 can send data via a stream connection 708 to a networkedendpoint 702 such as a laptop or a mobile device. The stream connection708 can use RTMP to stream data. The server 700 can access a document704, that includes hint media data, via a data interface 706 such as amemory bus, network interface, or a disk drive interface. Hint mediadata can include multiple hint samples 710, 712, 714, 716 with varioustypes of sample payloads, e.g., video, audio, text. Hint samples withdifferent sample payload types can be multiplexed into a single hintsegment, which can increase server throughput. In some implementations,a single hint segment can interleave different media types. For example,a single hint segment can include hint sample payloads that respectivelyalternate between two or more media types.

In some implementations, the server 700 can access the document 704stored on a disk drive and can store the document 704 in memory such asa random access memory for a future access. The server 700 can accesshint samples 710, 712, 714, 716 in the document 704 in a transmissionorder sequence, which can be determined by their arrangement in thedocument 704. The server 700 can send RTMP messages that are based onrespective hint samples 710, 712, 714, 716 over the stream connection708. In some implementations, the server 700 can send messages based onthe transmission order sequence. In some implementations, the server 700can perform one or more byte swap operations to prepare data packetscontaining hint samples 710, 712, 714, 716 for transmission over anetwork. The endpoint 702 can receive RTMP messages that are based onthe hint samples 710, 712, 714, 716 to render media content.

FIG. 8 shows an example of a media content streaming technique. Anendpoint can stream media content such as a movie to another endpointsuch as a remote device. For example, an server can communicate with aremote device to stream media content to the remote device (805). Insome implementations, the server can access a media document based on arequest from the remote device.

An endpoint can access hint information associated with the mediacontent (810). The hint information can include message headers arrangedin a transmission order sequence. A message header can correspond to amedia data sample. A message header can include a message streamidentifier, a message type identifier, a timestamp, and a message lengthvalue. In some implementations, hint information can include samplesassociated with one or more media types such as audio, video, or text.For example, the hint information can include samples associated withdifferent media types. In some implementations, hint information caninclude pointers associated with one or more media types such as audio,video, or text. For example, the hint information can include pointersassociated with different media types.

An endpoint can transmit one or more data streams to a remote device(815). The data stream can include messages arranged in the transmissionorder sequence. For example, the endpoint can stream messages based onthe messages headers and corresponding payload information in the hintinformation.

In some implementations, a hint sample can include multiple media datasamples. In some implementations, multiple hint samples can include thesame media data sample. In some implementations, a hint media datasegment can include hint samples with pointers to media data samples andcan include hint samples with media data samples. In someimplementations, hint samples can be transmitted to a client, which canuse the hint samples to render media content. In some implementations, aserver can transmit hint samples to an intermediate endpoint which canuse the hint samples to deliver media content to a client. Anintermediate endpoint can use different communication techniques such asdifferent network protocols for sending and receiving hint information.In some implementations, a server can add hint samples to a document andcan cache hint samples for future use.

In some implementations, a server can access protected media content ina document. In some implementations, a server can protect media contentbefore distribution to clients. In some implementations, a server canuse one or more digital rights management (DRM) techniques to controlaccess privileges associated with media content. In someimplementations, a server can encrypt media content and controldistribution of associated key material to decrypt said media content.In some implementations, a server can use an ADOBE® DRM system,available from Adobe Systems Incorporated of San Jose, Calif.

Embodiments of the subject matter and the operations described in thisspecification can be implemented in digital electronic circuitry, or incomputer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Embodiments of the subject matterdescribed in this specification can be implemented as one or morecomputer programs, i.e., one or more modules of computer programinstructions, encoded on computer storage medium for execution by, or tocontrol the operation of, data processing apparatus. Alternatively or inaddition, the program instructions can be encoded on anartificially-generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially-generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application-specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub-programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, e.g., an FPGA (field programmable gate array) or an ASIC(application-specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for performing actions in accordance with instructions andone or more memory devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom or transfer data to, or both, one or more mass storage devices forstoring data, e.g., magnetic, magneto-optical disks, or optical disks.However, a computer need not have such devices. Moreover, a computer canbe embedded in another device, e.g., a mobile telephone, a personaldigital assistant (PDA), a mobile audio or video player, a game console,a Global Positioning System (GPS) receiver, or a portable storage device(e.g., a universal serial bus (USB) flash drive), to name just a few.Devices suitable for storing computer program instructions and datainclude all forms of non-volatile memory, media and memory devices,including by way of example semiconductor memory devices, e.g., EPROM,EEPROM, and flash memory devices; magnetic disks, e.g., internal harddisks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROMdisks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

To provide for interaction with a user, embodiments of the subjectmatter described in this specification can be implemented on a computerhaving a display device, e.g., a CRT (cathode ray tube) or LCD (liquidcrystal display) monitor, for displaying information to the user and akeyboard and a pointing device, e.g., a mouse or a trackball, by whichthe user can provide input to the computer. Other kinds of devices canbe used to provide for interaction with a user as well; for example,feedback provided to the user can be any form of sensory feedback, e.g.,visual feedback, auditory feedback, or tactile feedback; and input fromthe user can be received in any form, including acoustic, speech, ortactile input. In addition, a computer can interact with a user bysending documents to and receiving documents from a device that is usedby the user; for example, by sending web pages to a web browser on auser's client device in response to requests received from the webbrowser.

Embodiments of the subject matter described in this specification can beimplemented in a computing system that includes a back-end component,e.g., as a data server, or that includes a middleware component, e.g.,an application server, or that includes a front-end component, e.g., aclient computer having a graphical user interface or a Web browserthrough which a user can interact with an implementation of the subjectmatter described in this specification, or any combination of one ormore such back-end, middleware, or front-end components. The componentsof the system can be interconnected by any form or medium of digitaldata communication, e.g., a communication network. Examples ofcommunication networks include a local area network (“LAN”) and a widearea network (“WAN”), an inter-network (e.g., the Internet), andpeer-to-peer networks (e.g., ad hoc peer-to-peer networks).

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other. In someembodiments, a server transmits data (e.g., an HTML page) to a clientdevice (e.g., for purposes of displaying data to and receiving userinput from a user interacting with the client device). Data generated atthe client device (e.g., a result of the user interaction) can bereceived from the client device at the server.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyinventions or of what may be claimed, but rather as descriptions offeatures specific to particular embodiments of particular inventions.Certain features that are described in this specification in the contextof separate embodiments can also be implemented in combination in asingle embodiment. Conversely, various features that are described inthe context of a single embodiment can also be implemented in multipleembodiments separately or in any suitable subcombination. Moreover,although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingmay be advantageous. Moreover, the separation of various systemcomponents in the embodiments described above should not be understoodas requiring such separation in all embodiments, and it should beunderstood that the described program components and systems cangenerally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular embodiments of the subject matter have been described.Other embodiments are within the scope of the following claims. In somecases, the actions recited in the claims can be performed in a differentorder and still achieve desirable results. In addition, the processesdepicted in the accompanying figures do not necessarily require theparticular order shown, or sequential order, to achieve desirableresults. In certain implementations, multitasking and parallelprocessing may be advantageous.

1-20. (canceled)
 21. A method performed by data processing apparatus,comprising: accessing a document that comprises a hint segment, a mediametadata track, and a hint metadata track, wherein the hint segmentcomprises message headers interleaved with media data samples, whereinthe message headers are arranged within the hint segment in atransmission order sequence, wherein separate ones of the media datasamples are arranged as message payload data for corresponding ones ofthe message headers, wherein each of the message headers comprise amessage stream identifier, a message type identifier, a timestamp, and amessage length value, wherein the hint metadata track includes pointersto respective ones of the message headers, wherein the media metadatatrack includes pointers to respective associated ones of the media datasamples; and generating a data stream to stream media content of thedocument, the data stream comprising messages arranged in thetransmission order sequence, wherein each of the messages are based on adifferent one of the message headers and a corresponding different oneof the media data samples.
 22. The method of claim 21, wherein the hintsegment comprises a first message header of the message headers, asecond message header of the message headers, and a first media datasample associated with audio data interleaved with a second media datasample associated with video data, the first message headercorresponding to the first media data sample, and the second messageheader corresponding to the second media data sample.
 23. The method ofclaim 21, wherein the media metadata track is a first media metadatatrack, wherein the document includes a second media metadata track,wherein the first media metadata track includes, in lieu of samples, oneor more pointers to corresponding one or more first samples of the mediadata samples within the hint segment, and wherein the second mediametadata track includes, in lieu of samples, one or more pointers tocorresponding one or more second samples of the media data sampleswithin the hint segment, wherein the one or more second samples aredifferent from the one or more first samples.
 24. The method of claim21, further comprising: transmitting the data stream to a remote device.25. The method of claim 24, wherein transmitting the data stream to theremote device comprises transmitting the data stream in accordance witha Real-Time Messaging Protocol (RTMP), wherein each message header isarranged according to a RTMP message header format.
 26. The method ofclaim 24, wherein transmitting the data stream to the remote devicecomprises multiplexing first messages that include audio data withsecond messages that include video data on the data stream.
 27. Themethod of claim 21, further comprising: operating a server to delivermultiple streams to remote devices based on the hint segment.
 28. Anon-transitory computer storage medium encoded with a computer program,the program comprising instructions that when executed by dataprocessing apparatus cause the data processing apparatus to performoperations comprising: accessing a document that comprises a hintsegment, a media metadata track, and a hint metadata track, wherein thehint segment comprises message headers interleaved with media datasamples, wherein the message headers are arranged within the hintsegment in a transmission order sequence, wherein separate ones of themedia data samples are arranged as message payload data forcorresponding ones of the message headers, wherein each of the messageheaders comprise a message stream identifier, a message type identifier,a timestamp, and a message length value, wherein the hint metadata trackincludes pointers to respective ones of the message headers, wherein themedia metadata track includes pointers to respective associated ones ofthe media data samples; and generating a data stream to stream mediacontent of the document, the data stream comprising messages arranged inthe transmission order sequence, wherein each of the messages are basedon a different one of the message headers and a corresponding differentone of the media data samples.
 29. The computer storage medium of claim28, wherein the hint segment comprises a first message header of themessage headers, a second message header of the message headers, and afirst media data sample associated with audio data interleaved with asecond media data sample associated with video data, the first messageheader corresponding to the first media data sample, and the secondmessage header corresponding to the second media data sample.
 30. Thecomputer storage medium of claim 28, wherein the media metadata track isa first media metadata track, wherein the document includes a secondmedia metadata track, wherein the first media metadata track includes,in lieu of samples, one or more pointers to corresponding one or morefirst samples of the media data samples within the hint segment, andwherein the second media metadata track includes, in lieu of samples,one or more pointers to corresponding one or more second samples of themedia data samples within the hint segment, wherein the one or moresecond samples are different from the one or more first samples.
 31. Thecomputer storage medium of claim 28, the operations further comprising:transmitting the data stream to a remote device.
 32. The computerstorage medium of claim 31, wherein transmitting the data stream to theremote device comprises transmitting the data stream in accordance witha Real-Time Messaging Protocol (RTMP), wherein each message header isarranged according to a RTMP message header format.
 33. The computerstorage medium of claim 31, wherein transmitting the data stream to theremote device comprises multiplexing first messages that include audiodata with second messages that include video data on the data stream.34. A system comprising: a computer storage device configured to storeinformation comprising a document that contains a hint segment, a mediametadata track, and a hint metadata track, wherein the hint segmentcomprises message headers interleaved with media data samples, whereinthe message headers are arranged within the hint segment in atransmission order sequence, wherein separate ones of the media datasamples are arranged as message payload data for corresponding ones ofthe message headers, wherein each of the message headers comprise amessage stream identifier, a message type identifier, a timestamp, and amessage length value, wherein the hint metadata track includes pointersto respective ones of the message headers, wherein the media metadatatrack includes pointers to respective associated ones of the media datasamples; and a data processing apparatus configured to performoperations comprising (i) accessing the document, and (ii) generating adata stream to stream media content of the document, the data streamcomprising messages arranged in the transmission order sequence, whereineach of the messages are based on a different one of the message headersand a corresponding different one of the media data samples.
 35. Thesystem of claim 34, wherein the hint segment comprises a first messageheader of the message headers, a second message header of the messageheaders, and a first media data sample associated with audio datainterleaved with a second media data sample associated with video data,the first message header corresponding to the first media data sample,and the second message header corresponding to the second media datasample.
 36. The system of claim 34, wherein the media metadata track isa first media metadata track, wherein the document includes a secondmedia metadata track, wherein the first media metadata track includes,in lieu of samples, one or more pointers to corresponding one or morefirst samples of the media data samples within the hint segment, andwherein the second media metadata track includes, in lieu of samples,one or more pointers to corresponding one or more second samples of themedia data samples within the hint segment, wherein the one or moresecond samples are different from the one or more first samples.
 37. Thesystem of claim 34, the operations further comprising: transmitting thedata stream to a remote device.
 38. The system of claim 37, whereintransmitting the data stream to the remote device comprises transmittingthe data stream in accordance with a Real-Time Messaging Protocol(RTMP), wherein each message header is arranged according to a RTMPmessage header format.
 39. The system of claim 37, wherein transmittingthe data stream to the remote device comprises multiplexing firstmessages that include audio data with second messages that include videodata on the data stream.
 40. The system of claim 34, wherein the dataprocessing apparatus includes the computer storage device.